 |
 |
 |
 |
 |
| Feed |
delabs
Technologies |
Search | Contact | Service |
Voltage measurement attenuator amp - del20013LF356 opamp FET input is in a inverting amplifier configuration here. R4 + R5 make up Ri each 1/4 W MFR withstands 250V so both will take upto 500V. Use more in series for higher voltage withstand with care in PCB layout and cabinet insulation.Rf is selected by a digital value at A-B inputs of 4052, that way R1, R2, R3, R6 are selected for four ranges giving various attenuation levels. The important thing in this circuit is the on resistance of 4052 of 100 ohms comes in series with the output resistance of opamp, so the output is taken before the cmos switch . The output of this digital attenuator should not be loaded and should be buffered before use. Gain = Av = Rf/Ri and Vout = -(Rf/Ri) * Vin To view the circuit below, Click the Link of PNG or PDF and view the Circuit, PNG can be Scrolled with Mouse and PDF can be Viewed-Zoomed in the Browsers with Acrobat plugin. The Javascript and Images must be enabled in your Browser. |
| PNG-Schematic
PDF-Circuit DSN-Source |
| Voltage measurement attenuator amp - del20013 |
| Rf and Ri are 0.1% MFR,
if costly, use bourns 10T trimpot or a
difficult way use series parallel combination and scratch 10% part of a network R to increase value. (first remove paint on resistor with a blade then with ohmmeter connected scrape black film to increment value till done, seal in dust free unit). I have also made a OpAmp Calculator which you can use to calculate Values. Inverting Opamp Interactive Gadget Tutor Data sheets and info useful to study and build this circuit. Not that i studied them, i had no internet when i designed these, they later invented the web, thank you for that. |